Simple logic lies behind US President George W. Bush's missile defence strategy - Americans want protection.
There is nothing new about such an idea - it has been used by Republicans and Democrats as a vote-puller for five decades. Republicans, though, are most closely associated with the concept, which has become a pillar of their ideology.
Politicians are in a bind. With terrorism on American soil the biggest perceived threat, they have little choice but to follow their political instincts. Republicans want a missile defence so that they can be labelled 'pro-defence', while Democrats, even though they do not want such a system, back it because they fear being called 'anti-defence'.
As a presidential candidate in May 2000, Mr Bush said it was time 'to leave the Cold War behind and defend against the new threats of the 21st century'.
A year later and in the White House, he outlined his missile defence plans. The 1972 Anti-Ballistic Missile Treaty has since been scrapped.
Since the start of the missile age during World War II, when German V2s spawned fear in London, US administrations have been searching for better ways to defend their country.
The Cold War sparked the arms race and weapons proliferation, but the collapse of the Soviet Union has not meant a change of attitude. Rather, it has meant an upsurge in fear of rogue states.